Prior art filter methods include, for example, mechanical filtration—a physical retention of particles larger than the pores of the filter media; electrostatic filtration—adhering particles to fibers in the filter without killing/deactivating the particles; and filtration as taught and claimed in U.S. Pat. No. 5,980,827 which issued to the inventor hereof on Nov. 9, 1999 and is entitled “Disinfection Of Air Using An Iodine/Resin Disinfectant.” It has been determined that improved iodinated resin filtration occurs in a thin media when the product is incorporated to a media with a convoluted pathway. By forcing the microorganism/toxin to pass through a circuitous route, the microorganism/toxin is eventually killed/deactivated. One method for providing a circuitous route is to employ a nonwoven media.
In published U.S. patent application number 20010045398 entitled “Process For The Immobilisation Of Particles In A Three Dimensional Matrix Structure” the non-woven material is first produced and then an iodinated resin, such as the one disclosed in U.S. Pat. No. 5,639,452 (the '452 patent) is added using alcohol or a partial solvent with a high pulsation vacuum pump that opens the filter pores so that the active agent will go through it (the “Triosyn” resin). The contents of the '452 patent is incorporated by reference in its entirety herein.
U.S. Pat. No. 6,346,125 teaches incorporating an aqueous antimicrobial agent into a non-electrostatically charged non-woven material. Specifically, the '125 patent describes a particular process for incorporating an aqueous antimicrobial agent into a non-electrostatically charged non-woven. However, without the electrostatic properties, the non-woven must be of greater thickness so that the microorganism has sufficient contact time with the antimicrobial agent for decontamination.
U.S. Pat. No. 5,952,092 teaches a non-woven fabric with chemically active particles. However, this patent does not teach using an electrostatic substrate as in the present innovation.
Nonwoven electrets and methods of manufacturing the same are known in the art. For example, U.S. Pat. No. 5,409,766 describes a nonwoven fabric in an electret state composed of monofilaments formed of a polymer composition capable of dust collection over a prolonged time and in a hot and humid condition. Also disclosed are processes for producing this nonwoven fabric, as well as a filtering air masking material composed of that nonwoven fabric. However, this prior art system does not provide antimicrobial/antitoxin properties. Thus, the microorganism/toxin, while suspended within the nonwoven fabric, is not sterilized or deactivated. Once the electrostatic properties of the nonwoven are depleted or the material is saturated, the microorganism/toxin may be released back into the atmosphere.
Electrostatically charged filters are known to be used in facemasks, for example. With respect to both, one of the problems of face seal is well known and represents a limitation that the industry has been trying to address. The problem resides in the fact that from one morphological physical structure of a human being or structure to the next the differences generate such a wide spectrum of geometrical deviations that it has been difficult to create a 100% airtight seal. For a facemask the difficulty in creating a seal occurs between the skin and the mask for a range of face sizes and shapes. Various different technological means have been tried, for example using, adhesive seals, flat and wide seals and resilient material seals. The industry has oriented its work on creating an airtight seal, however, the pressure differential generated actually forces air in the gaps between seal and skin thus bypassing the air filter material. The electrostatic filter of the present invention may be made of a spongy or other breathable nonwoven material so as to minimize the pressure differential, thus preventing air from being forced through the gaps. Further, it effectively makes the gasket used to create a closure between the user and the facemask out of a thin filter having a low-pressure drop like the electrostatic filter and having the added benefit of the active agent incorporated thereon.
Other known prior art that teach the use of high pressure drop media includes the mechanical filtration of the HEPA filter. However, the pressure drop of the present invention is approximately 50% to 90% lower than that of the HEPA filter alone. The filter further includes a material that kills on passage vegetative bacteria, spores, and viruses. They are filtered out of the airstream and are killed. In addition, the present invention is self-sterilizing, meaning that not only does it filter air passed there through, it kills the bacteria trapped on the filter. Therefore, the media protects both the user and the outside air.
Given the shortcomings of the prior art, it is advantageous to have an electret, which has improved characteristics over known solutions. The present innovation comprises a substrate that supports an active agent and is a dielectric.